The power to determine how something behaves, and the means of exercising it. Control implies someone holds it, and that it can be handed over.

The declared surface where two things meet and may act on each other. An interface is a promise about what may be asked.

To shape one signal by another — a voice through knobs, a wave riding a wave. The turning of a sound into its other selves without losing the throat it came from.

A bounded surface set into a larger one. Also a small group convened to judge.

To change from one state to another, and the thing that makes the change. Two positions, and nothing between them.